Controlling device for radiocommunication



Sept. 15, 1925.

C. A. FRIEDRICH CONTROLLING DEVICE FOR RADIO COMMUNICATION Filed Aug. 16, 1924 Q INVENTOR M Zflwk;

?atente d Sept. 15, 1925- i STATES A'ENT OFFICE.

CHARLES A. FRIEDRICH, OF BROOKLYN, NEW YORK.

CONTROLLING DEVICE FOR RADIOCOMMUNIGATION.

Application filed August 16, 1924. Serial No. 732,409.

- cation, it has been found that most of such devices did not give accurate enough adjustments to make them suitable for this purpose and, therefore, most of them have been abandoned in the laboratory. The main difliculty in such mercury controlling devices seems to be due to the faulty construction and the material used for the mercury containers. I have found that the container, in order to permit the use of mercury as a controlling element, must be so constructed that the surface tension thereof will cause the mercury to always move as a continuous mass, i. e. the cohesion of the molecules of the mercury will be increased to resist the attraction or adhesion of the walls of the container, which latter tends to break up the mercury mass. Incidentally, the curved ends of the mercury mass result ing from such construction will afford minute' adjustments.

This I accomplish by using a circular container of which one or both face walls are spherically curved or convexed, so that the mercury mass fillingonly a part of the container will diminish in thickness from the center toward the periphery of the container and by reason of the greater weight at its wider or thicker part, the surface tension thereof will be considerably enhanced, as a result of which the molecules at the narrower parts will resist the force of adhesion exerted by the walls of the chamber.

Having thus overcome the difiiculties in the use of mercury as a controlling element, I have found I can readily make use 'of'this element in the construction of grid leaks, rheostats, variable condensers. and the like, thereby greatly simplifying the same and increasing the efficiency thereof.

In describing my new mercury controlling devices, I wish it to be expressly understood that since instead of mercury other liquids may be adopted to act as controlling elements without departing from the principle of my invention, I do not wish to limit myself to devices using mercury only.

In the accompanying drawing showing a few embodiments of my invention, Fig. 1-

is a face view of a grid leak; Fig. 2 is a vertical section thereof; Fig. 3 is a vertical section of a combination grid leak and con denser; Fig. 4: is a section on line H of Fig. 3; Fig. 5 is a face view of a rheostat.

In Iiigs. 1 and 2, a grid leak constructed according to my invention is shown. The same comprises a circular disc 10 of mica or other dielectric material on which I provide close to the circumferential edge a circularly curved means of high resistance, such as a lead or india ink line 11 drawn on said disc. Preferably, for greater accuracy of control, this line may be made of varying thickness to gradually diminish in width toward one of its ends, as at 11 while the opposite end 11 is bent outwardly and continued on a short flap 10 projecting from the circumference of the disc. This flap is perforated, as at 10 through the end 11 of the lead line and serves as one terminal of the grid leak. Suitably fixed and hermetically sealed, as at 14;, to the disc 10 over the sensitized face thereof, is an outwardly convexed cover 13 of glass or other suitable dielectric material, the circumferential edgeof which coincides with the edge of the disc. I have found that very good results are obtained when the cover 13 is given a convexity of 4: radius. The hermetically sealed space 8 between the disc and cover constitutes a chamber or' container for a mass of'mercury 15 previously dropped onto the disc and whose quantity is preferably less than one-half of the volume of the container. By reason of the increased surface tension, as heretofore explained, the lateral edges of said mass will be rounded and have the tendency to retain their shape at all times.

Mounted in the chamber around the central axis, is a circularly curved split wire 12 of conducting material, one end of which is bent in radial direction, as at 12', and then axially, as at 12 to pass. outwardly through a central perforation 13' of the cover and to serve as the second terminal of the grid leak. The wire 12 is suitably fixed in said perforation and is thereby retained the resistance.

in its position within the chamber. By corresponding admeasurement of the Wire 12, sensitive line 11 and of the mercury mass, the latter will, when the disc is held in a vertical position, always overlap with its upper edge of the wire 12 and make contact with it and is capable, when the disc is turned on its horizontal axis in a certain direction, of overlapping the sensitized line 11 and in moving along said lineof decreasing the effective length thereof, thereby varying Thus when, as shown, the device is rotated on its horizontal axis clockwise, the mercury mass will cover more and more of the sensitized part 11, lessening the resistance and when turned in the opposite direction, the mercury will recede along said mark increasing the resistance.

The devicemay be attached to a spindle 16, which can be rotatively mounted in the panel P of a radio set and may carry the usual dial D,

In Figs. 3 and 4, the hereinbefore described grid leak is shown combined with a condenser. To this end, I attach to the back of the mica disk 10 a condenser of usual construction consisting substantially of alternate layers of conducting and non-conducting material, such as tin-foil sheets 17 and mica, parafiine covered paper sheets or the like 18. The cover 13, disc 10 and condenser may be hermetically sealed together, as at 14:. One of the end tin-foil sheets may be conductively connected to the end 11' of the lead line 11 on the flap 10' of the disc 10 and the other end tin-foil sheet may be conductivelyconnected to the extended end 12 of the conductor or wire 12. The mercury element 15 is contained in the chamber 8 between the cover 13 and disc 10.

The same principle underlying the construction of the grid leak can be applied to that of a rheostat, with the exception that while in the grid leak the mercury acts merely as a contact element and the resistance is formed by the curved sensitized mark, with a rheostat, two conductor wires are used, the mercury overbridging the space between said conductors acting as resistance. Thus according to Fig. 5, the construction of the container 10, 13 and the conductor 12 is the same as in the foregoing modification. But instead of the sensitized mark 11, I employ a conductor wire 20. The latter is so arranged in the chamber .9 that the gap between it and the wire 12 will gradually in crease from one end toward the opposite end thereof. This I best accomplish by curving the wire 20 eccentrically to the circular central wire 12. The point 20 of said wire nearest to the circumference of the wire 12 is projected outwardly through the cover 13 and serves as the other terminal of the rheostat, one terminal being formed by'the part 12 of the circular wire '12 as before. When the device is held in vertical position (say with the points 20 and 12 lying in a vertical plane) the mercury mass 15 will in overlapping the wire 12 and the inner end of the wire 20 overbridge the largest gap he tween the two conductors and being a poorer conductor of electricity than the latter produce the greatest resistance. On turning the device on its horizontal axis, say anti-clockwise, the mercury mass will be caused to gradually reduce the gap, diminishing the resistance (as indicated by the arrows) until it reaches the point 20, when the shortest gap is overbridged and thereby the resistance reduced to a minimum.

What I claim is 1. In an electric controlling device for radio communication, an outwardly bulging container adapted to be turned on its axis, insulated electric conducting elements and a liquid element therein, the latter being capable of being constantly in contact with one of said conducting elements and when turning said container of being displaced, so as to gradually overlap in an increasing or dccreasing manner the other of said conducting elements.

2. In an electric controlling device for radio communication, an outwardly bulging container of dielectric material adapted to be turned on its axis, insulated electric conducting elements and a liquid element therein, the latter being adapted to control the passage of electricity between said conducting elements and being capable of being con stantly in uniform contact with one of said conducting elements and when turning said container of being displaced, so as to gradually vary the electric property of the other of said conducting elements.

3. In an electric controlling device for radio communication, a con'iparatively flat.

outwardly bulging container of dielectric material, insulated electric conducting ele ments therein, of which one encircles the center of said container and a liquid element in said container, the latter being capable of being constantly in contact with said circular conducting element and when turning said container on its axis of being displaced so as to gradually increase or decrease the electric property ofthe other conducting element.

4. In an electric controlling device for radio communication, a disc shaped outwardly bulging container of dielectric material adapted to be turned on a horizontal axis, insulated electric conducting elements carried thereby a mass of mercury in said container capable of being constantly in contact with one of said conducting elements and when turning said container of gradually varying the electric property of the other of said elements.

5. In a controlling device for radio comtainer of gradually overlapping said resist-- munication, a disc shaped outwardly bulge ing container of dielectric material, insulated electric conducting elements carried thereby, one of said elements encircling the center of said container and leading outwardly toiform a terminal, the other conducting element leading to another terminal, and a liquid element in said container capable of being constantly in contact with said circular element and when turning said container on its horizontal axis of gradually varying the electric property of the other conducting element.-

6. In a resistance controlling device for radio communication, a disc shaped container of dielectric material adapted to be turned on its horizontal axis and having at least one outwardly bulging face wall, an electric conducting-element encircling the center of said container and one end of which leads outwardly to form a terminal, acurved high resistance element in said container and a mercury mass. capable of being constantly in contact with said circular conducting element and when turning said conance element in an increasing or decreasing manner.

7. In a id leak, a disc shaped container of dielectric material adapted to be turned on its horizontal axis and having at least one outwardly bulging face wall, an electric conductor encircling the center of said container, and one end of ,which serves as a terminal, a curved element of high resistance material near the periphery of said container and whose one end serves as the second terminal and a mercury mass in said container capable of being constantly in contact with said first contact member and when turning said container on its axis,

of increasing or decreasing the effective length of said resistance element.

8. In a rheostat, a disc shaped container of dielectric material having at least one outwardly bulging face wall, an. electric conductor encircling the center of said container and one end of which serves as a terminal, another conductor extending through said container at a gradually varying distance from saidfirst conductor and whose one end projects outwardly and serves as the second terminal and a mercury mass in said container capable of constantly making contact with the first named conductor and when turning said container on its axis of overlapping the other conductor in a gradually increasing or decreasing manner and thereby varying the resistance between said conductors.

9. In a mercury controlling device for radio communication, a disc shaped mercury container of dielectric material adapted to be turned on its horizontal central axis and having at least one outwardly bulging face wall of such radius, that the surface tension of the mercury will overcome the force of attraction exerted upon the latter by the adjoining edges of the container.

'10. In a liquid controlling device for radio communication, a comparatively flat liquid container having at least one outwardly bulging face wall of such radius as to increase or decrease the surface tension of said liquid, according to the nature of the latter, and toy thereby shape the level thereof.

In testimony whereof I afiix my signature.

CHARLES A. FRIEDRICH. 

